First find out how much each bead costs. In this case, it is .24 (48/200=.24) Now you simply multiply .24 by 25, equaling 6. She will have to pay 6 more dollars.
What you need to do is add the two equations and combine like terms to get h(x). Refer to the photo for a better explanation.
0.4% of $4,800 is $19.2, otherwise written as $19.20 in terms of money, apparently. This is based off the calculations of a calculator, though if you prefer to do the rough work, be my guest. The work for finding it on raw work is below.
(EX.) EQUATION : y = p% × x
EQUATION : y = 0.4% × 4800
To make this work, you gotta convert that percent into a decimal, by dividing the percentage by 100. 0.4 ÷ 100 = 0.004
EQUATION : y = 0.004 × 4800.
Once you multiply them, you get : 19.2 (otherwise known as $19.20)
Well you need an equation because how many friends were at the party? x*12x10=w thats your equation or however you want to put it. the letters are your variables